U.S. Pat. No. 3,255,322 issued June 7, 1966 discloses a regulator by-pass switch in which the by-pass element is pivotally mounted at one end and pivotally connected at its opposite end with a link whose movement is responsive to opening of the main disconnect switch to effect closing of the by-pass switch. This operating link is said to constitute a part of a toggle structure for holding the by-pass switch closed. The toggle linkage as disclosed is said to be maintained in a position to hold the by-pass switch closed by means of a spring and the resilient action of a pair of loop contacts between which the by-pass switch element is said to be sandwiched also is said to aid in holding the by-pass switch element closed. This arrangement may not effect a positive and secure latching action whereby the by-pass switch is positively locked in closed position in view of the somewhat uncertain action of the resilient loop contacts and of the toggle biasing spring.